It has previously been proposed to construct a continuous chain of batteries by properly collating a series of layers each of which contains intermittent electrode deposits and then sealing around each positive electrode and its opposite negative electrode. For examples of these processes see U.S. Pat. Nos. 3,004,093; 3,004,094; and 3,494,796. The previously proposed processes are ones in which the seals are accomplished by continuously moving the collation of layers past a pair of stationary pressure rolls; see U.S. Pat. Nos. 3,004,093 and 3,004,094.
A thoroughly liquid-impervious seal is essential around each positive electrode and its opposite negative electrode. Failure to achieve such a seal permits liquid to escape from the interior of the battery, resulting in reduced battery performance and shelf life and possibly resulting also in corrosion of surrounding objects.
Three factors associated with the sealing process--heat, pressure, and time--affect the degree and hence the quality of the seals. The magnitude of the time factor may be varied within a considerable range if the remaining two factors are properly adjusted. However, the conclusion is justified that truly high quality seals cannot be obtained by using stationary energy platens (e.g., pressure rolls or any other energy transferring mechanisms) together with a continuously moving collation of layers. This conclusion is based on the requirement that there is some minimum amount of time during which heat and/or pressure must be applied to get good seals, and that this minimum time is in excess of the time during which pressure is applied by the pressure rolls of the aforementioned previous processes, at least when the collated layers are moved at the speeds required for modern, economical production methods.
In U.S. Pat. No. 3,708,349 a method of constructing batteries is described which involves a collation of layers containing intermittent deposits of positive and negative electrodes. Liquid-impervious seals are required around opposed pairs of positive and negative electrodes. It is desirable that the collation of layers described in U.S. Pat. No. 3,708,349 move continuously throughout most if not all of the manufacturing process.
In U.S. Pat. No. 3,701,690 it is proposed to impregnate patches of adhesive having the configuration of closed loops into battery separator material and then to include those loops in collated layers of battery materials where the adhesive patches provide liquid-impervious seals around opposed pairs of positive and negative electrodes. The proposal disclosed in U.S. Pat. No. 3,701,690 may be used together with the construction method shown in U.S. Pat. No. 3,708,349.
It has previously been proposed that a pair of reciprocating platens could be used to press battery electrode active material in sheet form into moving grids; see U.S. Pat. No. 3,003,015.